to represent the value of the flux of the bit threads described by the component flow \({\vec{v}_{ij}}\)  passing through the \(\alpha \)  surface, where \(h\)  is the determinant of the induced metric on the surface \(\alpha \) , and \({\hat{n}_\alpha }\)  is the unit normal vector on surface \(\alpha \) . Due to the divergenceless property of bit threads, the \(F{(\alpha )_{ij}}\)  associated with each component flow does not depend on the surfaces the threads pass through in the bulk, and thus can be abbreviated as \( {F_{ij}} \) . In the framework of the locking bit thread scheme, the flux \( {F_{ij}} \)  of each thread bundle in a locking thread configuration characterizes the amount of the entanglement between the two regions it connects. In this simple case, it is easy to obtain [1]}
\(\begin{array}{l}{F_{AB}} = \frac{1}{2}\left( {{S_A} + {S_B} - {S_C}} \right) \equiv \frac{1}{2}{I_{AB}}\\{F_{AC}} = \frac{1}{2}\left( {{S_A} + {S_C} - {S_B}} \right) \equiv \frac{1}{2}{I_{AC}}\\{F_{BC}} = \frac{1}{2}\left( {{S_B} + {S_C} - {S_A}} \right) \equiv \frac{1}{2}{I_{BC}}\end{array},\) 
